Bumblebee is one of the smallest and physically weakest Autobots. While his stature allows him to do his job better than most Autobots could manage, he is self-conscious about his size. Maybe this is why he makes fast friends among the humans. He looks up (so to speak) to the other Autobots, especially Optimus Prime, but what he doesn't realize is that they look up to him. He may be small, but he's brave, and he's one of the most well-liked Autobots around. Bumblebee already has the respect he craves.